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1.
PLoS One ; 15(2): e0228643, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32017793

RESUMO

Filamentous fungi reproduce asexually or sexually, and the processes of asexual and sexual development are tightly regulated by a variety of transcription factors. In this study, we characterized a Zn2Cys6 transcription factor in two Aspergillus species, A. nidulans (AN5859) and A. flavus (AFLA_046870). AN5859 encodes a Zn2Cys6 transcription factor, called ZcfA. In A. nidulans, ΔzcfA mutants exhibit decreased fungal growth, a reduction in cleistothecia production, and increased asexual reproduction. Overexpression of zcfA results in increased conidial production, suggesting that ZcfA is required for proper asexual and sexual development in A. nidulans. In conidia, deletion of zcfA causes decreased trehalose levels and decreased spore viability but increased thermal sensitivity. In A. flavus, the deletion of the zcfA homolog AFLA_046870 causes increased conidial production but decreased sclerotia production; these effects are similar to those of zcfA deletion in A. nidulans development. Overall, these results demonstrate that ZcfA is essential for maintaining a balance between asexual and sexual development and that some roles of ZcfA are conserved in Aspergillus spp.


Assuntos
Aspergillus flavus/fisiologia , Aspergillus nidulans/fisiologia , Fatores de Transcrição/fisiologia , Aspergillus flavus/crescimento & desenvolvimento , Aspergillus nidulans/crescimento & desenvolvimento , Proteínas Fúngicas/fisiologia , Metaloproteínas/fisiologia , Reprodução , Reprodução Assexuada , Especificidade da Espécie , Zinco
2.
PLoS One ; 15(1): e0227250, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31910244

RESUMO

Oomycete plant pathogens are difficult to control and routine genetic research is challenging. A major problem is instability of isolates. Here we characterize >600 field and single zoospore isolates of Phytophthora capsici for inheritance of mating type, sensitivity to mefenoxam, chromosome copy number and heterozygous allele frequencies. The A2 mating type was highly unstable with 26% of 241 A2 isolates remaining A2. The A1 mating type was stable. Isolates intermediately resistant to mefenoxam produced fully resistant single-spore progeny. Sensitive isolates remained fully sensitive. Genome re-sequencing of single zoospore isolates revealed extreme aneuploidy; a phenomenon dubbed Dynamic Extreme Aneuploidy (DEA). DEA is characterized by the asexual inheritance of diverse intra-genomic combinations of chromosomal ploidy ranging from 2N to 3N and heterozygous allele frequencies that do not strictly correspond to ploidy. Isolates sectoring on agar media showed dramatically altered heterozygous allele frequencies. DEA can explain the rapid increase of advantageous alleles (e.g. drug resistance), mating type switches and copy neutral loss of heterozygosity (LOH). Although the mechanisms driving DEA are unknown, it can play an important role in adaptation and evolution and seriously hinders all aspects of P. capsici research.


Assuntos
Aneuploidia , Phytophthora/fisiologia , Doenças das Plantas/microbiologia , Reprodução Assexuada/genética , Verduras/microbiologia , Alelos , Evolução Biológica , Mapeamento Cromossômico , Cucumis sativus/microbiologia , Variação Genética , Genótipo , Perda de Heterozigosidade , Phytophthora/isolamento & purificação , Polimorfismo de Nucleotídeo Único , Análise de Sequência de DNA , Análise de Célula Única , Esporos/genética
3.
PLoS Genet ; 15(12): e1008520, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31841515

RESUMO

Although most unicellular organisms reproduce asexually, most multicellular eukaryotes are obligately sexual. This implies that there are strong barriers that prevent the origin or maintenance of asexuality arising from an obligately sexual ancestor. By studying rare asexual animal species we can gain a better understanding of the circumstances that facilitate their evolution from a sexual ancestor. Of the known asexual animal species, many originated by hybridization between two ancestral sexual species. The balance hypothesis predicts that genetic incompatibilities between the divergent genomes in hybrids can modify meiosis and facilitate asexual reproduction, but there are few instances where this has been shown. Here we report that hybridizing two sexual Caenorhabditis nematode species (C. nouraguensis females and C. becei males) alters the normal inheritance of the maternal and paternal genomes during the formation of hybrid zygotes. Most offspring of this interspecies cross die during embryogenesis, exhibiting inheritance of a diploid C. nouraguensis maternal genome and incomplete inheritance of C. becei paternal DNA. However, a small fraction of offspring develop into viable adults that can be either fertile or sterile. Fertile offspring are produced asexually by sperm-dependent parthenogenesis (also called gynogenesis or pseudogamy); these progeny inherit a diploid maternal genome but fail to inherit a paternal genome. Sterile offspring are hybrids that inherit both a diploid maternal genome and a haploid paternal genome. Whole-genome sequencing of individual viable worms shows that diploid maternal inheritance in both fertile and sterile offspring results from an altered meiosis in C. nouraguensis oocytes and the inheritance of two randomly selected homologous chromatids. We hypothesize that hybrid incompatibility between C. nouraguensis and C. becei modifies maternal and paternal genome inheritance and indirectly induces gynogenetic reproduction. This system can be used to dissect the molecular mechanisms by which hybrid incompatibilities can facilitate the emergence of asexual reproduction.


Assuntos
Caenorhabditis/fisiologia , Hibridização Genética , Reprodução Assexuada , Animais , Caenorhabditis/genética , Feminino , Fertilidade , Masculino , Herança Materna , Partenogênese , Herança Paterna , Sequenciamento Completo do Genoma
4.
J Microbiol ; 57(12): 1115-1125, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31758396

RESUMO

Histone acetylation/deacetylation represent a general and efficient epigenetic mechanism through which fungal cells control gene expression. Here we report developmental requirement of MoHOS2-mediated histone deacetylation (HDAC) for the rice blast fungus, Magnaporthe oryzae. Structural similarity and nuclear localization indicated that MoHOS2 is an ortholog of Saccharomyces cerevisiae Hos2, which is a member of class I histone deacetylases and subunit of Set3 complex. Deletion of MoHOS2 led to 25% reduction in HDAC activity, compared to the wild-type, confirming that it is a bona-fide HDAC. Lack of MoHOS2 caused decrease in radial growth and impinged dramatically on asexual sporulation. Such reduction in HDAC activity and phenotypic defects of ΔMohos2 were recapitulated by a single amino acid change in conserved motif that is known to be important for HDAC activity. Expression analysis revealed up-regulation of MoHOS2 and concomitant down-regulation of some of the key genes involved in asexual reproduction under sporulation-promoting condition. In addition, the deletion mutant exhibited defect in appressorium formation from both germ tube tip and hyphae. As a result, ΔMohos2 was not able to cause disease symptoms. Wound-inoculation showed that the mutant is compromised in its ability to grow inside host plants as well. We found that some of ROS detoxifying genes and known effector genes are de-regulated in the mutant. Taken together, our data suggest that MoHOS2-dependent histone deacetylation is pivotal for proper timing and induction of transcription of the genes that coordinate developmental changes and host infection in M. oryzae.


Assuntos
Histona Desacetilases/genética , Histona Desacetilases/metabolismo , Magnaporthe/enzimologia , Magnaporthe/crescimento & desenvolvimento , Magnaporthe/metabolismo , Reprodução Assexuada/fisiologia , Parede Celular/metabolismo , Epigênese Genética , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Deleção de Genes , Regulação Fúngica da Expressão Gênica , Histona Desacetilases/química , Magnaporthe/genética , Modelos Moleculares , Mutagênese Sítio-Dirigida , Oryza/microbiologia , Fenótipo , Doenças das Plantas/microbiologia , Conformação Proteica , Processamento de Proteína Pós-Traducional , Reprodução Assexuada/genética , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/genética , Virulência/genética , Virulência/fisiologia
5.
Elife ; 82019 09 05.
Artigo em Inglês | MEDLINE | ID: mdl-31486772

RESUMO

Theory predicts that sexual reproduction can either facilitate or restrain transposable element (TE) accumulation by providing TEs with a means of spreading to all individuals in a population, versus facilitating TE load reduction via purifying selection. By quantifying genomic TE loads over time in experimental sexual and asexual Saccharomyces cerevisiae populations, we provide direct evidence that TE loads decrease rapidly under asexual reproduction. We show, using simulations, that this reduction may occur via evolution of TE activity, most likely via increased excision rates. Thus, sex is a major driver of genomic TE loads and at the root of the success of TEs.


Assuntos
Elementos de DNA Transponíveis , Evolução Molecular , Reprodução Assexuada , Saccharomyces cerevisiae/crescimento & desenvolvimento , Saccharomyces cerevisiae/genética , Simulação por Computador
6.
PLoS Genet ; 15(9): e1008394, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31536509

RESUMO

Courtship is pivotal for successful mating. However, courtship is challenging for the Cryptococcus neoformans species complex, comprised of opportunistic fungal pathogens, as the majority of isolates are α mating type. In the absence of mating partners of the opposite mating type, C. deneoformans can undergo unisexual reproduction, during which a yeast-to-hyphal morphological transition occurs. Hyphal growth during unisexual reproduction is a quantitative trait, which reflects a strain's ability to undergo unisexual reproduction. In this study, we determined whether unisexual reproduction confers an ecological benefit by promoting foraging for mating partners. Through competitive mating assays using strains with different abilities to produce hyphae, we showed that unisexual reproduction potential did not enhance competition for mating partners of the same mating type, but when cells of the opposite mating type were present, cells with enhanced hyphal growth were more competitive for mating partners of either the same or opposite mating type. Enhanced mating competition was also observed in a strain with increased hyphal production that lacks the mating repressor gene GPA3, which contributes to the pheromone response. Hyphal growth in unisexual strains also enables contact between adjacent colonies and enhances mating efficiency during mating confrontation assays. The pheromone response pathway activation positively correlated with unisexual reproduction hyphal growth during bisexual mating and exogenous pheromone promoted bisexual cell fusion. Despite the benefit in competing for mating partners, unisexual reproduction conferred a fitness cost. Taken together, these findings suggest C. deneoformans employs hyphal growth to facilitate contact between colonies at long distances and utilizes pheromone sensing to enhance mating competition.


Assuntos
Cryptococcus neoformans/genética , Genes Fúngicos Tipo Acasalamento/genética , Reprodução Assexuada/fisiologia , Comunicação Celular , Fusão Celular , Cryptococcus/genética , Cryptococcus/patogenicidade , Cryptococcus neoformans/patogenicidade , Proteínas Fúngicas/genética , Genes Fúngicos Tipo Acasalamento/fisiologia , Hifas/genética , Feromônios , Reprodução/genética , Reprodução Assexuada/genética
7.
BMC Evol Biol ; 19(1): 170, 2019 08 14.
Artigo em Inglês | MEDLINE | ID: mdl-31412772

RESUMO

BACKGROUND: In the absence of sex and recombination, genomes are expected to accumulate deleterious mutations via an irreversible process known as Muller's ratchet, especially in the case of polyploidy. In contrast, no genome-wide mutation accumulation was detected in a transcriptome of facultative apomictic, hexaploid plants of the Ranunculus auricomus complex. We hypothesize that mutations cannot accumulate in flowering plants with facultative sexuality because sexual and asexual development concurrently occurs within the same generation. We assume a strong effect of purging selection on reduced gametophytes in the sexual developmental pathway because previously masked recessive deleterious mutations would be exposed to selection. RESULTS: We test this hypothesis by modeling mutation elimination using apomictic hexaploid plants of the R. auricomus complex. To estimate mean recombination rates, the mean number of recombinants per generation was calculated by genotyping three F1 progeny arrays with six microsatellite markers and character incompatibility analyses. We estimated the strength of purging selection in gametophytes by calculating abortion rates of sexual versus apomictic development at the female gametophyte, seed and offspring stage. Accordingly, we applied three selection coefficients by considering effects of purging selection against mutations on (1) male and female gametophytes in the sexual pathway (additive, s = 1.000), (2) female gametophytes only (s = 0.520), and (3) on adult plants only (sporophytes, s = 0.212). We implemented recombination rates into a mathematical model considering the three different selection coefficients, and a genomic mutation rate calculated from genome size of our plants and plant-specific mutation rates. We revealed a mean of 6.05% recombinants per generation. This recombination rate eliminates mutations after 138, 204 or 246 generations, depending on the respective selection coefficients (s = 1.000, 0.520, and 0.212). CONCLUSIONS: Our results confirm that the empirically observed frequencies of facultative recombination suffice to prevent accumulation of deleterious mutations via Muller's ratchet even in a polyploid genome. The efficiency of selection is in flowering plants strongly increased by acting on the haplontic (reduced) gametophyte stage.


Assuntos
Acúmulo de Mutações , Ranunculus/genética , Recombinação Genética , DNA de Plantas/análise , DNA de Plantas/genética , Repetições de Microssatélites , Taxa de Mutação , Óvulo Vegetal , Poliploidia , Ranunculus/crescimento & desenvolvimento , Ranunculus/fisiologia , Reprodução Assexuada
8.
Nature ; 572(7771): 655-659, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31413361

RESUMO

Differential coordination of growth and patterning across metazoans gives rise to a diversity of sizes and shapes at tissue, organ and organismal levels. Although tissue size and tissue function can be interdependent1-5, mechanisms that coordinate size and function remain poorly understood. Planarians are regenerative flatworms that bidirectionally scale their adult body size6,7 and reproduce asexually, via transverse fission, in a size-dependent manner8-10. This model offers a robust context to address the gap in knowledge that underlies the link between size and function. Here, by generating an optimized planarian fission protocol in Schmidtea mediterranea, we show that progeny number and the frequency of fission initiation are correlated with parent size. Fission progeny size is fixed by previously unidentified mechanically vulnerable planes spaced at an absolute distance along the anterior-posterior axis. An RNA interference screen of genes for anterior-posterior patterning uncovered components of the TGFß and Wnt signalling pathways as regulators of the frequency of fission initiation rather than the position of fission planes. Finally, inhibition of Wnt and TGFß signalling during growth altered the patterning of mechanosensory neurons-a neural subpopulation that is distributed in accordance with worm size and modulates fission behaviour. Our study identifies a role for TGFß and Wnt in regulating size-dependent behaviour, and uncovers an interdependence between patterning, growth and neurological function.


Assuntos
Padronização Corporal/fisiologia , Tamanho Corporal/fisiologia , Planárias/crescimento & desenvolvimento , Planárias/fisiologia , Fator de Crescimento Transformador beta/metabolismo , Via de Sinalização Wnt/fisiologia , Animais , Padronização Corporal/genética , Tamanho Corporal/genética , Sistema Nervoso Central/citologia , Mecanorreceptores/citologia , Mecanorreceptores/fisiologia , Planárias/anatomia & histologia , Planárias/citologia , Interferência de RNA , Reprodução Assexuada/fisiologia , Via de Sinalização Wnt/genética
9.
Exp Appl Acarol ; 78(4): 535-546, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31363947

RESUMO

The red palm mite, Raoiella indica Hirst, is a threat to coconut, banana and native Arecaceae and Heliconiaceae in Brazil. This mite originated in the Eastern Hemisphere and was first reported in 2004 in the Americas, where the pest is spreading quickly and causing severe damage to its host plants. The objective of this work was to determine the life-history parameters of R. indica at constant temperatures, estimate its thermal requirements [threshold temperature (Tb) and thermal constant (K)] and also compare its life table parameters between sexual reproduction and parthenogenesis. The life tables were constructed on leaflets of Adonidia merrillii at 15, 20, 24, 27, 30 and 34 °C and 65% RH and a 12-h photoperiod. The longevity and the number of laid eggs of non-copulated adult females were evaluated at 27 °C. Raoiella indica had complete development, from egg to adult, only at 20, 24, 27 and 30 °C. At 15 °C, the eggs did not hatch, and at 34 °C, the mites survived only until the larval stage. For sexual reproduction, the optimal temperature was 27 °C, under which the reproductive parameters were higher. The reproductive parameters for sexual reproduction were higher than those for parthenogenesis. The Tb was 14.79 °C, and the thermal constant was 208.33 degree days. The life parameters estimated in this study can be used for modelling and predicting the population growth of R. indica in the field and consequently for improving their management strategies.


Assuntos
Traços de História de Vida , Ácaros/fisiologia , Animais , Brasil , Feminino , Larva/crescimento & desenvolvimento , Larva/fisiologia , Tábuas de Vida , Longevidade , Masculino , Ácaros/crescimento & desenvolvimento , Ninfa/crescimento & desenvolvimento , Ninfa/fisiologia , Reprodução , Reprodução Assexuada , Temperatura
10.
Ying Yong Sheng Tai Xue Bao ; 30(6): 2087-2092, 2019 Jun.
Artigo em Chinês | MEDLINE | ID: mdl-31257783

RESUMO

The scyphozoan genus Aurelia is one of the main contributors causing jellyfish blooms in global coastal waters. The population and reproduction of polyps are important factors to the outbreak of jellyfish. In this study, the effects of different salinity on the survival and asexual reproduction of Aurelia coerulea polyps were explored, which were cultured at the high (21 ℃) and low temperature (12 ℃), respectively. The results showed that more than 90% polyps could survive in the salinity range of 15-40 at the high temperature, with a range of salinity for budding being 20-32 and an optimum value of 28. The polyps were able to produce podocysts to tolerate low (≤15) and high (≥36) salinity conditions. At the low temperature, the survival rates of polyps were more than 90% in the salinity range of 20-40. The polyps could produce more buds in the salinity range of 20-32, with an optimum of 28. The salinity range of 20-40 was suitable for strobilation, with an optimum range of 28-32. It is concluded that the polyps of Aurelia coerulea can tolerate wide salinity variations, and that the salinity in a certain range has no significant influence on the asexual reproduction of polyps.


Assuntos
Salinidade , Cifozoários/fisiologia , Temperatura , Animais , Reprodução , Reprodução Assexuada
11.
Methods Mol Biol ; 1910: 331-369, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31278670

RESUMO

A major current molecular evolution challenge is to link comparative genomic patterns to species' biology and ecology. Breeding systems are pivotal because they affect many population genetic processes and thus genome evolution. We review theoretical predictions and empirical evidence about molecular evolutionary processes under three distinct breeding systems-outcrossing, selfing, and asexuality. Breeding systems may have a profound impact on genome evolution, including molecular evolutionary rates, base composition, genomic conflict, and possibly genome size. We present and discuss the similarities and differences between the effects of selfing and clonality. In reverse, comparative and population genomic data and approaches help revisiting old questions on the long-term evolution of breeding systems.


Assuntos
Cruzamentos Genéticos , Evolução Molecular , Genoma , Genômica , Reprodução Assexuada/genética , Composição de Bases , Cruzamento , Elementos de DNA Transponíveis , Genética Populacional , Tamanho do Genoma , Genômica/métodos , Genótipo , Hibridização Genética , Meiose/genética , Ploidias , Recombinação Genética , Seleção Genética , Segregação Social
12.
Malar J ; 18(1): 222, 2019 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-31262304

RESUMO

BACKGROUND: The ability of malaria (Plasmodium) parasites to adjust investment into sexual transmission stages versus asexually replicating stages is well known, but plasticity in other traits underpinning the replication rate of asexual stages in the blood has received less attention. Such traits include burst size (the number of merozoites produced per schizont), the duration of the asexual cycle, and invasion preference for different ages of red blood cell (RBC). METHODS: Here, plasticity [environment (E) effects] and genetic variation [genotype (G) effects] in traits relating to asexual replication rate are examined for 4 genotypes of the rodent malaria parasite Plasmodium chabaudi. An experiment tested whether asexual dynamics differ between parasites infecting control versus anaemic hosts, and whether variation in replication rate can be explained by differences in burst size, asexual cycle, and invasion rates. RESULTS: The within-host environment affected each trait to different extents but generally had similar impacts across genotypes. The dynamics of asexual densities exhibited a genotype by environment effect (G×E), in which one of the genotypes increased replication rate more than the others in anaemic hosts. Burst size and cycle duration varied between the genotypes (G), while burst size increased and cycle duration became longer in anaemic hosts (E). Variation in invasion rates of differently aged RBCs was not explained by environmental or genetic effects. Plasticity in burst size and genotype are the only traits making significant contributions to the increase in asexual densities observed in anaemic hosts, together explaining 46.4% of the variation in replication rate. CONCLUSIONS: That host anaemia induces several species of malaria parasites to alter conversion rate is well documented. Here, previously unknown plasticity in other traits underpinning asexual replication is revealed. These findings contribute to mounting evidence that malaria parasites deploy a suite of sophisticated strategies to maximize fitness by coping with, or exploiting the opportunities provided by, the variable within-host conditions experienced during infections. That genetic variation and genotype by environment interactions also shape these traits highlights their evolutionary potential. Asexual replication rate is a major determinant of virulence and so, understanding the evolution of virulence requires knowledge of the ecological (within-host environment) and genetic drivers of variation among parasites.


Assuntos
Adaptação Fisiológica/genética , Interação Gene-Ambiente , Variação Genética/fisiologia , Plasmodium chabaudi/fisiologia , Reprodução Assexuada , Animais , Feminino , Camundongos , Camundongos Endogâmicos C57BL , Plasmodium chabaudi/genética , Reprodução Assexuada/genética
13.
Microbiol Spectr ; 7(4)2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31325285

RESUMO

While disease and outbreaks are mainly clonal for bacteria and other asexually reproducing organisms, sexual reproduction in schistosomes and other helminths usually results in unique individuals. For sexually reproducing organisms, the traits conserved in clones will instead be conserved in the group of organisms that tends to breed together, the population. While the same tools are applied to characterize DNA, how results are interpreted can be quite different at times (see another article in this collection, http://www.asmscience.org/content/journal/microbiolspec/10.1128/microbiolspec.AME-0002-2018). It is difficult to know what the real effect any control program has on the parasite population without assessing the health of this population, how they respond to the control measure, and how they recover, if they do. This review, part of the Microbiology Spectrum Curated Collection: Advances in Molecular Epidemiology of Infectious Diseases, concentrates on one approach using pooled samples to study schistosome populations and shows how this and other approaches have contributed to our understanding of this parasite family's biology and epidemiology. *This article is part of a curated collection.


Assuntos
Schistosoma/fisiologia , Esquistossomose/parasitologia , Animais , Humanos , Epidemiologia Molecular , Reprodução Assexuada , Schistosoma/genética , Schistosoma/crescimento & desenvolvimento , Esquistossomose/epidemiologia
14.
PLoS Genet ; 15(6): e1008206, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31194741

RESUMO

The septation initiation network (SIN), composed of a conserved SepH (Cdc7p) kinase cascade, plays an essential role in fungal cytokinesis/septation and conidiation for asexual reproduction, while the mitogen-activated protein kinase (MAPK) pathway depends on successive signaling cascade phosphorylation to sense and respond to stress and environmental factors. In this study, a SepH suppressor-PomA in the filamentous fungus A. nidulans is identified as a negative regulator of septation and conidiation such that the pomA mutant is able to cure defects of sepH1 in septation and conidiation and overexpression of pomA remarkably suppresses septation. Under the normal cultural condition, SepH positively regulates the phosphorylation of MAPK-HogA, while PomA reversely affects this process. In the absence of PbsB (MAPKK, a putative upstream member of HogA), PomA and SepH are unable to affect the phosphorylation level of HogA. Under the osmostress condition, the induced phosphorylated HogA is capable of bypassing the requirement of SepH, a key player for early events during cytokinesis but not for MobA/SidB, the last one in the core SIN protein kinase cascade, indicating the osmotic stimuli-induced septation is capable of bypassing requirement of SepH but unable to bypass the whole SIN requirement. Findings demonstrate that crosstalk exists between the SIN and MAPK pathways. PomA and SepH indirectly regulate HogA phosphorylation through affecting HogA-P upstream kinases.


Assuntos
Aspergillus nidulans/genética , Proteínas Fúngicas/genética , Proteínas Quinases Ativadas por Mitógeno/genética , Reprodução Assexuada/genética , Aspergillus nidulans/crescimento & desenvolvimento , Proteínas de Ciclo Celular/genética , Citocinese/genética , Mutação/genética , Proteínas Nucleares/genética , Pressão Osmótica , Fosforilação/genética , Polimorfismo de Nucleotídeo Único/genética , Proteínas Quinases/genética , Proteínas Serina-Treonina Quinases/genética , Proteínas Tirosina Quinases/genética , Schizosaccharomyces/genética , Schizosaccharomyces/crescimento & desenvolvimento , Proteínas de Schizosaccharomyces pombe/genética , Transdução de Sinais/genética
15.
PLoS Genet ; 15(6): e1008211, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31194744

RESUMO

Although evolutionary transitions from sexual to asexual reproduction are frequent in eukaryotes, the genetic bases of these shifts remain largely elusive. Here, we used classic quantitative trait analysis, combined with genomic and transcriptomic information to dissect the genetic basis of asexual, parthenogenetic reproduction in the brown alga Ectocarpus. We found that parthenogenesis is controlled by the sex locus, together with two additional autosomal loci, highlighting the key role of the sex chromosome as a major regulator of asexual reproduction. We identify several negative effects of parthenogenesis on male fitness, and different fitness effects of parthenogenetic capacity depending on the life cycle generation. Although allele frequencies in natural populations are currently unknown, we discuss the possibility that parthenogenesis may be under both sex-specific selection and generation/ploidally-antagonistic selection, and/or that the action of fluctuating selection on this trait may contribute to the maintenance of polymorphisms in populations. Importantly, our data provide the first empirical illustration, to our knowledge, of a trade-off between the haploid and diploid stages of the life cycle, where distinct parthenogenesis alleles have opposing effects on sexual and asexual reproduction and may help maintain genetic variation. These types of fitness trade-offs have profound evolutionary implications in natural populations and may structure life history evolution in organisms with haploid-diploid life cycles.


Assuntos
Partenogênese/genética , Feófitas/genética , Reprodução Assexuada/genética , Cromossomos Sexuais/genética , Evolução Biológica , Genoma/genética , Haploidia , Estágios do Ciclo de Vida/genética , Feófitas/crescimento & desenvolvimento , Polimorfismo Genético , Locos de Características Quantitativas/genética
16.
BMC Evol Biol ; 19(1): 131, 2019 06 21.
Artigo em Inglês | MEDLINE | ID: mdl-31226928

RESUMO

BACKGROUND: A decade ago, the mixed reproductive strategy Asexual Queen Succession (AQS) was first described in termites. In AQS species, the workers, soldiers and dispersing reproductives are produced through sexual reproduction, while non-dispersing (neotenic) queens arise through automictic thelytokous parthenogenesis, replace the founding queen and mate with the founding king. As yet, AQS has been documented in six species from three lineages of lower (Rhinotermitidae) and higher (Termitinae: Termes group and Syntermitinae) termites. Independent evolution of the capacity of thelytoky as a preadaptation to AQS is supported by different mechanisms of automixis in each of the three clades. These pioneering discoveries prompt the question on the extent of thelytoky and AQS in the diversified family of higher termites. RESULTS: Here, we investigated the capacity of thelytoky and occurrence of AQS in three species from the phylogenetic proximity of the neotropical AQS species Cavitermes tuberosus (Termitinae: Termes group): Palmitermes impostor, Spinitermes trispinosus, and Inquilinitermes inquilinus. We show that queens of all three species are able to lay unfertilized eggs, which undergo thelytokous parthenogenesis (via gamete duplication as in C. tuberosus) and develop through the transitional stage of aspirants into replacement neotenic queens. CONCLUSIONS: The breeding system in P. impostor is very reminiscent of that described in C. tuberosus and can be characterized as AQS. In the remaining two species, our limited data do not allow classifying the breeding system as AQS; yet, also in these species the thelytokous production of neotenic females appears to be a systematic element of reproductive strategies. It appears likely that the capacity of thelytokous parthenogenesis evolved once in the Termes group, and may ultimately be found more widely, well beyond these Neotropical species.


Assuntos
Isópteros/classificação , Isópteros/fisiologia , Animais , Feminino , Isópteros/genética , Masculino , Repetições de Microssatélites , Partenogênese , Filogenia , Reprodução Assexuada
17.
BMC Evol Biol ; 19(1): 130, 2019 06 20.
Artigo em Inglês | MEDLINE | ID: mdl-31221097

RESUMO

BACKGROUND: Predicted genetic consequences of asexuality include high intraindividual genetic diversity (i.e., the Meselson effect) and accumulation of deleterious mutations (i.e., Muller's Ratchet), among others. These consequences have been largely studied in parthenogenetic organisms, but studies on fissiparous species are scarce. Differing from parthenogens, fissiparous organisms inherit part of the soma of the progenitor, including somatic mutations. Thus, in the long term, fissiparous reproduction may also result in genetic mosaicism, besides the presence of the Meselson effect and Muller's Ratchet. Dugesiidae planarians show outstanding regeneration capabilities, allowing them to naturally reproduce by fission, either strictly or combined with sex (facultative). Therefore, they are an ideal model to analyze the genetic footprint of fissiparous reproduction, both when it is alternated with sex and when it is the only mode of reproduction. RESULTS: In the present study, we generate and analyze intraindividual cloned data of a nuclear and a mitochondrial gene of sexual, fissiparous and facultative wild populations of the species Dugesia subtentaculata. We find that most individuals, independently of their reproductive strategy, are mosaics. However, the intraindividual haplotype and nucleotide diversity of fissiparous and facultative individuals is significantly higher than in sexual individuals, with no signs of Muller's Ratchet. Finally, we also find that this high intraindividual genetic diversity of fissiparous and facultative individuals is composed by different combinations of ancestral and derived haplotypes of the species. CONCLUSIONS: The intraindividual analyses of genetic diversity point out that fissiparous reproduction leaves a very special genetic footprint in individuals, characterized by mosaicism combined with the Meselson effect (named in the present study as the mosaic Meselson effect). Interestingly, the different intraindividual combinations of ancestral and derivate genetic diversity indicate that haplotypes generated during periods of fissiparous reproduction can be also transmitted to the progeny through sexual events, resulting in offspring showing a wide range of genetic diversity and putatively allowing purifying selection to act at both intraindividual and individual level. Further investigations, using Dugesia planarians as model organisms, would be of great value to delve into this new model of genetic evolution by the combination of fission and sex.


Assuntos
Planárias/genética , Planárias/fisiologia , Animais , Evolução Molecular , Variação Genética , Haplótipos , Ploidias , Reprodução , Reprodução Assexuada
18.
Bioessays ; 41(6): e1800246, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31087693

RESUMO

Here a wide distribution of meiotic machinery is shown, indicating the occurrence of sexual processes in all major eukaryotic groups, without exceptions, including the putative "asexuals." Meiotic machinery has evolved from archaeal DNA repair machinery by means of ancestral gene duplications. Sex is very conserved and widespread in eukaryotes, even though its evolutionary importance is still a matter of debate. The main processes in sex are plasmogamy, followed by karyogamy and meiosis. Meiosis is fundamentally a chromosomal process, which implies recombination and ploidy reduction. Several eukaryotic lineages are proposed to be asexual because their sexual processes are never observed, but presumed asexuality correlates with lack of study. The authors stress the complete lack of meiotic proteins in nucleomorphs and their almost complete loss in the fungus Malassezia. Inversely, complete sets of meiotic proteins are present in fungal groups Glomeromycotina, Trichophyton, and Cryptococcus. Endosymbiont Perkinsela and endoparasitic Microsporidia also present meiotic proteins.


Assuntos
Eucariotos/genética , Meiose/genética , Sexo , Evolução Biológica , Proteínas de Ciclo Celular/genética , Cromossomos/genética , Reparo do DNA/genética , Hereditariedade/genética , Estágios do Ciclo de Vida/genética , Filogenia , Ploidias , Recombinação Genética , Reprodução/genética , Reprodução Assexuada/genética
19.
mSphere ; 4(3)2019 05 08.
Artigo em Inglês | MEDLINE | ID: mdl-31068431

RESUMO

The human malaria parasite Plasmodium falciparum causes disease as it replicates within the host's erythrocytes. We have found that an erythrocyte serine hydrolase, acylpeptide hydrolase (APEH), accumulates within developing asexual parasites. Internalization of APEH was associated with a proteolytic event that reduced the size of the catalytic polypeptide from 80 to 55 kDa. A triazole urea APEH inhibitor, termed AA74-1, was employed to characterize the role of parasite-internalized APEH. In cell lysates, AA74-1 was a potent and highly selective inhibitor of both host erythrocyte and parasite-internalized APEH. When added to cultures of ring-stage parasites, AA74-1 was a poor inhibitor of replication over one asexual replication cycle; however, its potency increased dramatically after a second cycle. This enhancement of potency was not abrogated by the addition of exogenous isopentenyl pyrophosphate, the sole essential product of apicoplast metabolism. High-potency inhibition of parasite growth could be effected by adding AA74-1 to schizont-stage parasites, which resulted in parasite death at the early trophozoite stage of the ensuing replication cycle. Analysis of APEH inhibition in intact cultured cells revealed that host erythrocyte APEH, but not the parasite-internalized APEH pool, was inhibited by exogenous AA74-1. Our data support a model for the mode of parasiticidal activity of AA74-1 whereby sustained inactivation of host erythrocyte APEH is required prior to merozoite invasion and during parasite asexual development. Together, these findings provide evidence for an essential catalytic role for parasite-internalized APEH.IMPORTANCE Nearly half a million deaths were attributed to malaria in 2017. Protozoan parasites of the genus Plasmodium cause disease in humans while replicating asexually within the host's erythrocytes, with P. falciparum responsible for most of the mortality. Understanding how Plasmodium spp. have adapted to their unique host erythrocyte environment is important for developing malaria control strategies. Here, we demonstrate that P. falciparum coopts a host erythrocyte serine hydrolase termed acylpeptide hydrolase. By showing that the parasite requires acylpeptide hydrolase activity for replication, we expand our knowledge of host cell factors that contribute to robust parasite growth.


Assuntos
Eritrócitos/enzimologia , Eritrócitos/parasitologia , Interações Hospedeiro-Parasita , Peptídeo Hidrolases/metabolismo , Plasmodium falciparum/fisiologia , Reprodução Assexuada , Células Cultivadas , Humanos , Malária Falciparum/parasitologia , Plasmodium falciparum/crescimento & desenvolvimento , Proteínas de Protozoários/metabolismo
20.
Mol Biol Evol ; 36(9): 1902-1920, 2019 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-31077330

RESUMO

Hybridization and polyploidization are important evolutionary processes whose impacts range from the alteration of gene expression and phenotypic variation to the triggering of asexual reproduction. We investigated fishes of the Cobitis taenia-elongatoides hybrid complex, which allowed us to disentangle the direct effects of both processes, due to the co-occurrence of parental species with their diploid and triploid hybrids. Employing morphological, ecological, and RNAseq approaches, we investigated the molecular determinants of hybrid and polyploid forms. In contrast with other studies, hybridization and polyploidy induced relatively very little transgressivity. Instead, Cobitis hybrids appeared intermediate with a clear effect of genomic dosing when triploids expressed higher similarity to the parent contributing two genome sets. This dosage effect was symmetric in the germline (oocyte gene expression), interestingly though, we observed an overall bias toward C. taenia in somatic tissues and traits. At the level of individual genes, expression-level dominance vastly prevailed over additivity or transgressivity. Also, trans-regulation of gene expression was less efficient in diploid hybrids than in triploids, where the expression modulation of homoeologs derived from the "haploid" parent was stronger than those derived from the "diploid" parent. Our findings suggest that the apparent intermediacy of hybrid phenotypes results from the combination of individual genes with dominant expression rather than from simple additivity. The efficiency of cross-talk between trans-regulatory elements further appears dosage dependent. Important effects of polyploidization may thus stem from changes in relative concentrations of trans-regulatory elements and their binding sites between hybridizing genomes. Links between gene regulation and asexuality are discussed.


Assuntos
Cipriniformes/genética , Regulação da Expressão Gênica , Hibridização Genética , Poliploidia , Reprodução Assexuada , Animais , Cipriniformes/anatomia & histologia , Cipriniformes/metabolismo , Ecossistema , Feminino , Masculino , Fenótipo
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